Ammonite Fossils in Limestone Blocks Used for t...

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Ammonite Fossils in Limestone Blocks Used for the Castle Walls
Many castle walls in Okinawa have been built from Ryukyu Limestone which was formed from coral from tens or hundreds of thousands of years ago. However, the walls of Nakijin-jo Site use ancient limestones from the geological stratum of the surrounding area (the Nakijin stratum), which dates from the Mesozoic era, approximately 230 million years ago.
This limestone contains ammonite fossils, which lived in the oceans from between approximately 65 million to 400 million years ago. The ammonite is a relative of the squid and the octopus, and is related to the present-day nautilus. Forty-four different species of ammonite fossil have been discovered in the stratum around Nakijin Village, and are a valuable source of information in understanding the history of the Ryukyu Archipelago.